The present invention relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present invention relates to collapsible prosthetic heart valves that may be repositioned during the deployment procedure.
Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.
Collapsible prosthetic heart valves typically take the form of a valve assembly or structure mounted on a stent. There are many types of stents. However, two types of stents on which the valve structures are ordinarily mounted include a self-expanding stent and a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve must first be collapsed or crimped to reduce its circumferential size.
When a collapsed prosthetic valve has reached the desired implantation site in the patient (e.g., at or near the annulus of the patient's native heart valve), the prosthetic valve can be deployed or released from the delivery apparatus and expanded to the full operating size. For balloon-expandable stents, this generally involves releasing the entire valve, assuring its proper location, and then expanding a balloon positioned within the stent. For self-expanding stents, on the other hand, the stent automatically expands as the sheath covering the valve is withdrawn.
Some of the stents used in constructing collapsible replacement valves may have relatively sharp points or edges at the proximal and/or distal ends. The inventors have found that such sharp points or edges may penetrate into an anatomical feature and/or cause undesirable injury to the surrounding tissue during deployment or redeployment. Indeed, if a collapsible valve is moved from a first deployment location to another location, the likelihood of such injury may increase as a result of unintended tissue penetration and/or undesirable injury.
Therefore, there is a need for further improvements to the devices, systems, and methods for delivery of collapsible prosthetic heart valves, and in particular, self-expanding prosthetic heart valves.